Information about a substance can be derived through the interaction of light with that substance. The interaction changes characteristics of the light, for instance the frequency (and corresponding wavelength), intensity, polarization, and/or direction (e.g., through scattering, absorption, reflection or refraction). Chemical, thermal, physical, mechanical, optical or various other characteristics of the substance can be determined based on the changes in the characteristics of the light interacting with the substance. As such, in certain applications, one or more characteristics of crude petroleum, gas, water, or other wellbore fluids can be derived in-situ, e.g., downhole at well sites, as a result of the interaction between these substances and light.
An ICE selectively weights, when operated as part of optical analysis tools, light modified by a sample in a processing wavelength range such that the weighted light is related to one or more chemical or physical characteristics of the sample. The ICE includes an ICE core which measures the various sample characteristics through the use of regression techniques and one or more band-limiting filters which limit the measured characteristics to the processing wavelength range. Because ICEs extract information from the light modified by a sample passively, they can be incorporated in low cost and rugged optical analysis tools. Hence, ICE-based downhole optical analysis tools can provide a relatively low cost, rugged and accurate system for monitoring quality of wellbore fluids, for instance.
Like reference symbols in the various drawings indicate like elements.